The present invention relates to a liquid crystal display device, and more particularly to a structure for connecting a liquid crystal display panel to an integrated circuit (IC) for driving the display panel.
Since the liquid crystal display device can be driven by low voltage and low electric power, it is of advantage to a small portable electronic device such as an electronic wristwatch, a television receiver, and other similar devices. In order to provide a small portable electronic device, it is necessary to connect the IC (including LSI) to the liquid crystal display device by terminal dispositions of high density, and it is desirable to mount the IC on a substrate for electrodes of a liquid crystal display panel.
Conventional methods for connecting a liquid crystal display panel and the IC are as follows:
(1) A packaged IC is mounted on the electrode substrate by soldering; PA1 (2) An IC chip is disposed on a substrate and electrically connected to electrodes by wire bonding; PA1 (3) After an IC chip is electrically adhered to electrodes by conductive adhesives, the IC chip is protected by a cap.
However, these methods have disadvanteges. The first method is undesirable for providing a compact device of high density, because of the packaged IC. By the second method, an IC chip provided with a two-dimensional pad disposition can not be employed because of the limitation by wire bonding method per se. In the third method, the cap method has an inherent problem. The water vapor inevitably stays in a space between the IC chip and the cap, which causes the corrosion of wirings of circuits. In order to prevent the corrosion, the substrate and cap must be sealed by a hermetic seal. However, the temperature applied to the liquid crystal display panel having liquid crystal material must be maintained below 150.degree. C. in order to prevent the deterioration of the material, which means difficulty for the hermetic seal.